JP6616611B2 - Exhaust system - Google Patents

Description

  The present invention relates to an exhaust system used as a means for exhausting gas from a process chamber and other chambers in a semiconductor manufacturing apparatus, a flat panel display manufacturing apparatus, and a solar panel manufacturing apparatus, and in particular, the entire exhaust system. Therefore, it is possible to prevent gas condensation and early overheating in the vacuum pump without increasing the cost, and it is suitable for expanding the operating conditions of the entire exhaust system such as a gas flow rate capable of continuous exhaust.

  As shown in FIG. 12, this type of exhaust system S100 conventionally has, for example, first and second vacuum pumps P101 and P102 connected in series, and these vacuum pumps P101 and P102 and their connection C1 (specifically, Specifically, the gas containing condensable gas is exhausted through a pipe PL6 connecting the two vacuum pumps P101 and P102 and a valve VL1 provided in the middle of the pipe PL6. The first vacuum pump P101 is a turbo molecular pump, and the second vacuum pump P102 is a known positive displacement pump as a roughing pump.

  The condensability in the present application indicates the property of changing phase from gas to solid or liquid depending on pressure and temperature according to the characteristics of the vapor pressure curve.

  Further, in the conventional exhaust system S100, the turbo molecular pump (first vacuum pump P101) has less vibration due to the structural feature that the rotating body inside the pump is supported in a non-contact manner by a magnetic bearing. Used in a process chamber in a clean room.

  On the other hand, the positive displacement pump (second pump P102) is susceptible to vibration due to the structural feature that the rotating body is not supported in a non-contact manner inside the pump, so it is several meters away from the chamber and the turbo molecular pump. It is often used by installing it in a new location (for example, downstairs in a clean room). In the case of such a usage pattern, the following << Countermeasure 1 >> to << Countermeasure 3 >> are often taken in consideration of piping loss.

<< Countermeasure 1 >> A thick pipe PL6 having a diameter of about 75 mm to 100 mm is used as the pipe PL6 for connecting the turbo molecular pump (first vacuum pump P101) and the positive displacement pump (second vacuum pump P102).
<< Countermeasure 2 >> In order to set the outlet pressure of the pipe PL6 low, a large volume transfer pump (generally a Roots pump) is used as the second vacuum pump P102.
<< Countermeasure 3 >> The composite pump WP of FIG. 13 is used as the first vacuum pump P101 so that the exhaust operation can be performed even if the outlet pressure of the pipe PL6 is high.

  The composite pump WP of FIG. 13 is known as a pump of a type that combines the function of a turbo molecular pump and the function of a thread groove pump (see, for example, Patent Document 1).

  The turbo molecular pump function unit (blade exhaust mechanism 50) of the composite pump WP includes a plurality of rotor blades 51 provided on the outer peripheral surface of the rotor 54 and a pump case 55 that accommodates the rotor 54 as shown in FIG. A plurality of fixed blades 52 fixed to the peripheral surface are arranged in multiple stages, and the rotor blades 51 that rotate integrally with the rotor 54 and stationary stationary blades 52 impart momentum in a predetermined direction to gas molecules. The gas molecules in the chamber are exhausted from the suction port 56 toward the exhaust port 57. This also applies to the turbo molecular pump.

  By the way, when the above <Countermeasure 2> is implemented, the inlet pressure of the pipe PL6 connecting the turbo molecular pump (first vacuum pump P101) and the positive displacement pump (second vacuum pump P102) is relatively high. It becomes a high state (inlet pressure of the piping PL6 = pressure near the exhaust port 57 of the turbo molecular pump). The gas exhausted by these vacuum pumps P101 and 102 includes condensable gas. For this reason, in the gas compression process, the condensable gas in the gas condenses above its condensing pressure, and the condensed gas component accumulates inside the pump, thereby blocking the gas flow path of the turbo molecular pump, exhausting Problems such as performance degradation and overheating occur. There is also a problem that the condensed gas component deposits contact the rotor blades of the turbo-molecular pump and the rotor blades are damaged.

  Conventionally, as a countermeasure for gas condensation to avoid the above problem, the temperature in the vicinity of the exhaust port 57 of the turbo molecular pump (first vacuum pump P101) is kept higher than the condensing temperature of the condensable gas, so that the exhaust port is maintained. Gas condensation in the vicinity of 57 is prevented (see, for example, Patent Document 2).

  However, in the turbo molecular pump (first vacuum pump P101), heat generated by the exhaust operation (mainly frictional heat due to contact between gas and the rotor blades) is accumulated in the rotor blades. Under such circumstances, when the conventional countermeasures for gas condensation as described above, that is, the heat retention of the turbo molecular pump is performed, the heat retention heat is further accumulated in the rotor blades of the turbo molecular pump. The temperature of the rotor blades tends to become high, and the so-called early overheating problem that the temperature of the rotor blades reaches its heat resistance temperature relatively early causes the operating conditions of the entire exhaust system, such as the gas flow rate that allows continuous exhaust. There is a drawback of being limited.

  By the way, as a means for solving the problem of early overheating as described above, a method of performing so-called selective heating is also conceivable. The selective heat insulation can effectively prevent the heating unnecessary part from being heated more than necessary by insulating the heating necessary part from the other part (heating unnecessary part) and heating it.

  However, when the selective heating as described above is performed as an early countermeasure against overheating in the turbo molecular pump (the first vacuum pump P101), a high-pressure portion where gas condensation is particularly likely to occur in the turbo molecular pump, specifically, turbo molecules. Since a complicated heat insulation structure and heating structure in which only the vicinity of the exhaust port 57 of the pump is selectively insulated and heated are required, the cost of the entire exhaust system S100 must be increased.

JP2013-209928A JP 2014-29130 A

  The present invention has been made to solve the above-mentioned problems, and its purpose is to prevent gas condensation and premature overheating in the vacuum pump without causing an increase in the cost of the entire exhaust system. An object of the present invention is to provide an exhaust system suitable for expanding the operating conditions of the entire exhaust system, such as a gas flow rate that can be exhausted.

In order to achieve the above-mentioned object, the present invention connects a first vacuum pump and a second vacuum pump in series as at least two pumps, and a gas containing a condensable gas through these vacuum pumps and their connection parts. In the exhaust system for exhausting air, the second vacuum pump is installed in the vicinity of the first vacuum pump, and the internal pressure of the connection portion is lowered to flow through the inside of the connection portion. The environment is set so as to be included in the gas phase region below the vapor pressure curve of the condensable gas.

  In the present invention, the first vacuum pump and the second vacuum pump may be connected and integrated.

  In the present invention, a vibration proof structure may be provided in the connection portion.

  In the present invention, the first vacuum pump may be located upstream from the second vacuum pump and may be a turbo molecular pump.

In the present invention, the turbo molecular pump is provided with a wing exhaust mechanism for exhausting the gas in the rotor blades and the fixed blades may be characterized in that has a structure without the drag pumping mechanism.

  In the present invention, the second vacuum pump may be located downstream from the first vacuum pump and may be a positive displacement pump.

  In the present invention, the positive displacement pump includes a heater for heating the inside of the pump, a temperature sensor for measuring the temperature in the pump, and a heating temperature of the heater using a measurement value of the temperature sensor. And a temperature control circuit for controlling.

  In the present invention, the positive displacement pump may include an inverter circuit, and the rotation speed can be changed by the inverter circuit.

  In the present invention, the positive displacement pump may have a low-speed operation function that enables operation at a rotation speed lower than the rotation speed during normal operation.

  In the present invention, the control circuit of at least one of the first vacuum pump and the second vacuum pump is housed in a housing, and the housing is disposed in at least one of the housings. It is good also as the structure connected and integrated with the said vacuum pump.

  In the present invention, a heat insulating means may be provided at a connection portion between the first vacuum pump or the second vacuum pump and the housing of the control circuit.

  In the present invention, a third vacuum pump may be disposed and connected downstream of the second vacuum pump.

  In the present invention, the internal environment of the second vacuum pump is set to be an environment included in a solid phase region above the vapor pressure curve of the condensable gas flowing through the second vacuum pump. Also good.

  In the present invention, the internal environment of the second connection portion connecting the second vacuum pump and the third vacuum pump is higher than the vapor pressure curve of the condensable gas flowing through the interior. It may be characterized in that the environment is set to be included in the phase region.

  In the present invention, a trap or a storage tank that captures a condensed or solidified gas component is provided in the second connection portion that connects the second vacuum pump and the third vacuum pump. Also good.

  In the present invention, as a specific configuration of the exhaust system, as described above, by installing the second vacuum pump in the vicinity of the first vacuum pump, the environment inside the connection part of the two vacuum pumps is It set so that it might become the environment contained in the gaseous-phase area | region below the vapor pressure curve of the condensable gas which flows through the inside. For this reason, it is possible to prevent gas condensation in the connection part of both vacuum pumps and in the vicinity thereof (for example, in the vicinity of the exhaust port of the first vacuum pump close to the connection part), and in the connection part and the vicinity thereof. There is no need to implement measures to keep warm with a heater, that is, conventional gas condensation measures, and that heat is not additionally accumulated in vacuum pump components (for example, the rotor blades of a turbo molecular pump). Thus, it is possible to prevent so-called early overheating, and to provide an exhaust system suitable for expanding the operating conditions of the entire exhaust system, such as a gas flow rate capable of continuous exhaust.

  On the other hand, by combining the conventional countermeasure against gas condensation and the countermeasure of the present invention (the above-described environment setting in the present invention), it is possible to expand to gas types that could not be sufficiently exhausted and exhausted conventionally. Become.

  In addition, in the present invention, in order to prevent early overheating, a configuration in which a second vacuum pump is installed in the vicinity of the first vacuum pump instead of the conventional selective heating is employed. Since the heater used for gas condensation measures can be omitted, it is possible to reduce the number of parts and the cost of the entire exhaust system, and further to reduce the energy consumption of the entire system by reducing the heater power consumption.

The block diagram of the exhaust system which is one Embodiment of this invention. The vapor pressure curve figure for demonstrating the working principle of the exhaust system to which this invention is applied. Sectional drawing of the turbo-molecular pump employ | adopted as a 1st vacuum pump in the exhaust system of FIG. Sectional drawing for description of an anti-vibration structure. Sectional drawing for description of an anti-vibration structure. Sectional drawing for description of a heat insulation means. Explanatory drawing of the example which applied the capture | acquisition means in the exhaust system of FIG. The block diagram of the exhaust system which is other embodiment of this invention. The block diagram of the exhaust system which is other embodiment of this invention. 1 is a cross-sectional view of a turbo molecular pump that can be employed as a first vacuum pump that constitutes an exhaust system according to an embodiment of the present invention. Explanatory drawing of piping which comprises the connection part of a 1st vacuum pump and a 2nd vacuum pump. The block diagram of the conventional exhaust system. The block diagram of a composite pump.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram of an exhaust system according to an embodiment of the present invention, and FIG. 2 is a vapor pressure curve diagram for explaining the operating principle of the exhaust system to which the present invention is applied.

  In the exhaust system S1 of FIG. 1, first and second vacuum pumps P1 and P2 are connected in series as at least two pumps, and a gas containing a condensable gas is supplied through these vacuum pumps P1 and P2 and a connection portion C1 thereof. Exhaust.

  The gas exhausted by the exhaust system S1 exists in a chamber (not shown) to which the first vacuum pump P1 is connected, and from the chamber, the first vacuum pump P1, the connection part C1, and the second vacuum pump C2 By sequentially shifting, the air is exhausted out of the chamber.

  As the chamber, for example, a process chamber constituting a semiconductor manufacturing apparatus, a flat panel display manufacturing apparatus, a solar panel manufacturing apparatus, or the like is assumed, but the gas is exhausted from a chamber other than the process chamber. The exhaust system S1 shown in FIG.

  Basic technique for preventing gas condensation in the connection portion C1 and in the vicinity thereof (specifically, in the vicinity of the gas exhaust port closest to the connection portion C1 in the entire first vacuum pump P1). As an ideal idea, in the exhaust system S1 of FIG. 1, by installing the second vacuum pump P2 in the vicinity of the first vacuum pump P1, the environment inside the connection portion C1 is changed to the condensable gas flowing through the inside. The environment is set to be included in the gas phase region below the vapor pressure curve VPC (see FIG. 2). Such an environment setting is hereinafter referred to as “gas condensation countermeasure in the present invention”.

  By connecting the first vacuum pump P1 and the second vacuum pump P2 by installing the second vacuum pump P2 near the first vacuum pump P1 as described above (for example, The distance of the connection pipe or the connection passage) is shortened, and the fluid frictional resistance of the gas flowing through the connection portion C1, such as the pipe resistance or the passage resistance in the connection portion C1, is reduced. From this, the above-mentioned “countermeasures for gas condensation in the present invention” is realized in that the pressure inside or near the connecting portion C1 can be kept low in the same manner as the vicinity of the exhaust port of the first vacuum pump P1. It becomes possible.

  In the following, “countermeasures for gas condensation in the present invention” will be described in detail with reference to FIG.

In the vapor pressure curve diagram of FIG. 2, VPC indicates the vapor pressure curve of the condensable gas flowing through the connecting portion C1.
Further, point A in FIG. 2 indicates that in the exhaust system S1 adopting the “gas condensation countermeasure in the present invention”, the inside of the connection portion C1 connecting the two vacuum pumps P1 and P2 and the first vacuum communicating with the inside. The relationship between pressure and temperature in the vicinity of the exhaust port of the pump P1 is shown.

  A point B in FIG. 2 is a first comparative example, and in the conventional exhaust system S100 (see FIG. 12) adopting the “conventional gas condensation countermeasure” described above, the first constituting the exhaust system S100. 1 shows the relationship between pressure and temperature in the vicinity of the exhaust port of one vacuum pump P101.

  A point C in FIG. 2 is a second comparative example, which is an example in the case where the conventional countermeasure against gas condensation is not adopted in the conventional exhaust system S100 of FIG. 12, and the second C constituting the exhaust system S100. 1 shows the relationship between pressure and temperature in the vicinity of the exhaust port of one vacuum pump P101.

  Referring to point C in FIG. 2, which is the second comparative example, if no measures against gas condensation are adopted, the environment near the exhaust port of the first vacuum pump P101 is condensable flowing through the inside. Since the environment is included in the solid phase region above the gas vapor pressure curve VPC, gas condensation occurs in the vicinity of the exhaust port of the first vacuum pump P101.

  On the other hand, referring to point A in FIG. 2, in the case of the present exhaust system S1 adopting the “gas condensation countermeasures in the present invention”, the inside of the connecting part C1 connecting the two vacuum pumps P1 and P2 and this. Since the environment in the vicinity of the exhaust port of the first vacuum pump P1 communicating with is an environment included in the gas phase region below the vapor pressure curve VPC of the condensable gas flowing inside the connection portion C1, the environment of the vacuum pump P1 Gas condensation does not occur near the exhaust port.

  By the way, referring to point B in FIG. 2, even in the conventional exhaust system S100 adopting “conventional gas condensation countermeasures”, the environment near the exhaust port of the first vacuum pump P101 is a condensable gas flowing through the exhaust port. Gas condensation is unlikely to occur in the vicinity of the exhaust port of the vacuum pump P101.

  However, this “conventional gas condensation countermeasure” is achieved by increasing the internal temperature of the conventional exhaust system S100 shown in FIG. 12 without decreasing the internal pressure of the connection part C1 of the two vacuum pumps P101 and P102. The environment near the exhaust port of the first vacuum pump P101 is an environment included in the gas phase region below the vapor pressure curve VPC. For this reason, in the conventional exhaust system S100 adopting the “conventional gas condensation countermeasure”, as described in the prior art, the first vacuum pump P101 is likely to have a problem of so-called early overheating.

  On the other hand, in the exhaust system S1 of FIG. 1, the "gas condensation countermeasure in the present invention" is the environment in the connection part C1 and in the vicinity of the exhaust port of the first vacuum pump P1. The environment is set so as to be included in the gas phase region below the vapor pressure curve VPC of the condensable gas flowing through the mouth, and as a specific means for such setting, the temperature inside the connecting portion C1 is raised. Since the method of lowering the internal pressure is adopted, the above-described problem of early overheating hardly occurs in the exhaust system S1 adopting the “gas condensation countermeasure in the present invention”.

  In addition, as another countermeasure against gas condensation in the present invention, the combination of the countermeasure for raising the temperature inside the connection section C1 and the countermeasure for lowering the pressure inside the connection section C1 as described above, It is also possible to set to be an environment included in the gas phase region.

  Referring to FIG. 1, the first vacuum pump P1 is located upstream of the second vacuum pump P2, and specifically employs the turbo molecular pump TP1 shown in FIG.

As shown in FIG. 3, the turbo molecular pump TP1 as the first vacuum pump P1 includes a blade exhaust mechanism 50 that exhausts gas with the rotary blade 51 and the fixed blade 52, and includes a Holbeck type, a Sigburn type, and a Gode type. etc., has a structure without the drag pumping mechanism for various formats.

The first reason that the turbo molecular pump TP1 is a structure without the drag pumping mechanism, drag pumping mechanism has a narrow flow path and the gap of the flow of gas, clogging of the channel or gap occurs at the deposit part deposited It is easy. Also, the second reason is that the drag pumping mechanism, the narrow flow path or gap the gas flows flow frictional resistance of the gas increases with like, since the pressure of the gas is increased, the pressure of the gas the set internal environment of the connecting portions C1 included in the gas phase region it is difficult to like by lowering the, that is, if having a drag pump function adopts "gas condensation measures in the present invention" It is difficult to do.

  Referring to FIG. 3, a turbo molecular pump TP1 as the first vacuum pump P1 includes, as specific pump components, a rotor 54 supported by a magnetic bearing 53 and a plurality of outer peripheral surfaces of the rotor 54. And a plurality of fixed blades 52 fixed to the inner peripheral surface of a pump case 55 that accommodates the rotor 54, and the plurality of rotary blades 51 and the fixed blades are arranged in multiple stages, A blade exhaust mechanism 50 is formed. In the turbo molecular pump TP1, the rotor blades 51 rotate integrally with the rotor 54, and the rotating rotor blades 51 and the stationary stationary blades 52 impart momentum to gas molecules in a predetermined direction. Gas molecules are exhausted from the suction port 56 toward the exhaust port 57.

  In addition, a lower part of the turbo molecular pump TP1 as the first vacuum pump P1 includes a water cooling plate 59 with a built-in water cooling pipe 58 in order to suppress the temperature rise of the entire pump due to heat generated in the exhaust operation. A cooling means 60 is provided.

  Referring to FIG. 1, the second vacuum pump P2 is located downstream from the first vacuum pump P1 (turbo molecular pump TP1) and is composed of a volumetric transfer pump DP1.

  In the exhaust system S1 of FIG. 1, a Roots pump (see FIG. 3) is adopted as a specific example of the positive displacement pump DP1, but the present invention is not limited to this. As another example of the positive displacement pump, various types of positive displacement pumps other than the roots type such as a screw type or a claw type can be adopted.

  As the positive displacement pump DP1, one having a heat retaining function can be adopted. The positive displacement pump DP1 in this case uses a heater (not shown) for heating the inside of the pump, a temperature sensor (not shown) for measuring the temperature in the pump, and a measured value by the temperature sensor. By providing a temperature control circuit (not shown) for controlling the heating temperature of the heater (for example, feedback control), a heat retaining function is realized.

  The positive displacement pump DP1 further includes an inverter circuit (a device that converts AC to AC again), and the rotation speed can be changed by the inverter circuit.

  The positive displacement pump DP1 has a low-speed operation function that enables operation at a rotational speed lower than the rotational speed during normal operation. This low speed operation function can be realized based on the rotation speed changing function by the inverter circuit.

  As shown in FIG. 1 and FIG. 3, the first vacuum pump P1 and the second vacuum pump P2 are connected and integrated via the connection portion C1 (pump connection integrated structure). When such a pump connection integrated structure is adopted, a communication hole H (see FIG. 3) is provided in the connection portion C1 of both the vacuum pumps P1 and P2. As shown in FIG. 3, one end of the communication hole H communicates with the exhaust port 57 of the first vacuum pump P1, and the other end of the communication hole H communicates with the intake port 70 of the second vacuum pump P2. Thus, the gas exhausted from the first vacuum pump P1 is sent to the second vacuum pump P2 side via the communication path H of the connection portion C1.

  The communication hole H is preferably formed to have a large diameter over the entire hole. A plurality of them may be installed. In such a case, the fluid frictional resistance of the gas flowing through the communication hole H is reduced, so that the pressure in the connection portion C1 and in the vicinity of the exhaust port 57 of the first vacuum pump P1 communicating with the connection portion C1 is reduced. This is because the “countermeasures for gas condensation in the present invention” can be easily adopted in that it can be maintained.

  By the way, when the pump connection integrated structure as described above is adopted, vibration generated in the second vacuum pump P2 may be transmitted to the first vacuum pump P1 and the upstream chamber via the connection portion C1. For example, when a volume transfer pump DP1 such as a Roots pump is employed as the second vacuum pump P2, a relatively large vibration is generated from the bearing portion of the rotating body and the timing gear for synchronizing the rotating body. To do.

  On the other hand, in the turbo molecular pump TP1 employed as the first vacuum pump P1, as shown in FIG. 3, the rotating body composed of the rotor 54 and the rotor blade 51 is supported by the magnetic bearing 53 in a non-contact manner. In the support state, control is performed so as to keep the gap between the rotating body and the surrounding fixed portion (specifically, the gap between the rotary blade 51 and the fixed blade 52) narrow.

  Therefore, if the vibration generated by the second vacuum pump P2 is transmitted to the operating turbo molecular pump TP1 (first vacuum pump P1) as described above, the rotating body is surrounded by the inside of the turbo molecular pump TP1. There is a risk that the turbo molecular pump TP1 may be broken, such as being damaged by contact with or colliding with the fixed portion. Therefore, it is necessary to reliably prevent the transmission of vibration from the positive displacement pump DP1 (second vacuum pump P2) to the turbo molecular pump TP1 (first vacuum pump P2).

  In addition, the suction port 56 of the turbo molecular pump TP1 is connected to a chamber, and precision processing and work such as semiconductor etching is performed in the chamber. Therefore, the positive displacement pump DP1 (second vacuum pump P2) It is also necessary to reliably prevent the vibration generated in step 1 from being finally transmitted to the chamber through the turbo molecular pump TP1 (first vacuum pump P1).

  Therefore, in the exhaust system S1 of FIG. 1, the first vacuum pump P1 is used as a means for effectively preventing the phenomenon that the vibration generated by the second vacuum pump P2 is transmitted to the first vacuum pump P1 and the upstream chamber. 4 or 5 is provided at the connection portion C1 between the first vacuum pump P2 and the second vacuum pump P2. Specific examples of this anti-vibration structure VC are << Anti-Vibration Structure 1-1 >> to << Anti-Vibration Structure 1-3 >> below.

<< Vibration-proof structure 1-1 >>
As shown in FIG. 4 or 5, the vibration-proof structure 1-1 is connected to the first vacuum pump P1 and the second vacuum pump P2 with a bolt BT1, and a rubber bush or the like is connected to the fastening connection portion. The vibration absorbers DN1 and DN2 are interposed to absorb the vibration of the second vacuum pump P2.

  When the first vacuum pump P1 and the second vacuum pump P2 are connected via the cooling means 60, that is, the cooling means is connected to the connection portion C1 between the first vacuum pump P1 and the second vacuum pump P2. When 60 is interposed, vibrations are generated between the first vacuum pump P1 and the cooling means 60 and between the second vacuum pump P2 and the cooling means 60, as shown in FIG. 4 or FIG. Absorbing materials DN1 and DN2 can be interposed.

  A predetermined gap G <b> 1 is formed between the second vacuum pump P <b> 1 and the cooling means 60 by the intervention of the vibration absorbing materials DN <b> 1 and DN <b> 2. The gap G1 may be provided between the first vacuum pump P1 and the cooling means 60, and either one of the vibration absorbing materials may be used depending on the magnitude of vibration generated by the second vacuum pump P2. It can be omitted.

  As this type of vibration absorbing material DN1, DN2, for example, a material having high heat resistance and low hardness such as silicone rubber is preferable.

<< Vibration-proof structure 1-2 >>
As shown in FIG. 4 or FIG. 5, the vibration-proof structure 1-2 employs a stepped bolt as the bolt BT1, and appropriately manages the crushing state of the vibration absorbing materials DN1, DN2, so that the bolt BT1 The gap G1 is prevented from disappearing due to excessive tightening or vibration of the second vacuum pump P2, and the vibration absorbing effect by the gap G1 and the vibration absorbing materials DN1 and DN2 is effectively exhibited. If the gap G1 disappears due to the fact that the vibration absorbing materials DN1 and DN2 are not properly crushed, the second vacuum pump P2 and the cooling means 60 are in direct contact with each other, or the first vacuum pump P1 and the cooling means. This is because the vibration prevention effect by the gap G1 and the vibration absorbing materials DN1 and DN2 is reduced by direct contact with 60.

<< Vibration-proof structure 1-3 >>
As shown in FIG. 5, the anti-vibration structure 1-3 inserts a cylindrical spacer SP into the communication hole H provided in the connection part C1 of the two vacuum pumps P1 and P2, and the spacer SP A structure in which annular elastic members RD1 and RD2 such as O-rings are attached to the outer peripheral surface of the upper end and the outer peripheral surface of the lower end, and the spacer SP is connected to the communication hole H and the exhaust port 57 of the first vacuum pump P1 through the annular elastic members RD1 and RD2. The configuration is set so as to be in a floating state. Thereby, the spring rigidity of the vibration transmission path passing through the periphery of the communication hole H is reduced, and the transmission of vibration from the second vacuum pump P1 to the first vacuum pump P1 is reduced. A bellows may be adopted instead of the spacer SP.

  Specifically, the vibration transmission in the vibration-proof structure 1-3 is reduced when the vibration of the second vacuum pump P2 is generated and the entire second vacuum pump P2 is a cone with the upper annular elastic member RD1 as a base point. By performing a motion similar to the pendulum motion, the transmission of vibration from the second vacuum pump to the first vacuum pump is reduced.

  4 includes the above << anti-vibration structure 1-1 >> and << anti-vibration structure 1-2 >>, and the anti-vibration structure VC in FIG. 5 includes the above << anti-vibration structure 1-3 >> and the above-mentioned It includes << Anti-Vibration Structure 1-1 >> and << Anti-Vibration Structure 1-2 >>.

  Referring to FIG. 3, the first vacuum pump P1 and the second vacuum pump P2 include a control circuit CC as means for controlling power supply to the pump, pump rotation speed, and the like. As a specific example of the installation structure of the control circuit CC, in the exhaust system S1 of FIG. 1, a housing as a circuit housing box is located below the first vacuum pump P1 and next to the second vacuum pump P2. A structure in which the control circuit CC is connected to and integrated with the first and second vacuum pumps P1 and P2 by providing the body BX and housing the control circuit CC in the housing BX (hereinafter referred to as “circuit / pump”). It is configured to be “integrated structure”.

  Between the connecting portion between the first vacuum pump P1 and the housing BX of the control circuit CC, specifically, between the cooling means 60 and the housing BX provided at the lower part of the first vacuum pump P1, the housing BX As means for preventing the occurrence of dew condensation in the interior, as shown in FIG. 6, a heat insulation means DD is provided.

  By the way, in the case where the circuit / pump integrated structure described above is employed, when the first vacuum pump P1 is cooled by the cooling means 60, the housing BX is also cooled by heat conduction, and condensation may occur in the housing BX. In this case, since the control circuit CC may malfunction or break down due to water droplets due to condensation, the heat insulating means DD prevents the occurrence of condensation by blocking such a heat conduction path.

  As a specific configuration example of the heat insulation means DD as described above, in the exhaust system S1 of FIG. 1, as shown in FIG. 6, heat insulation is provided between the water cooling plate 59 and the housing BX constituting the water cooling means 60. And a system in which a heat insulating collar (insulating collar) DC is installed around a bolt BT2 that fastens the water cooling plate 59 and the housing BX. Any one of the methods can be omitted as necessary. As a material of the heat insulating collar DC, stainless steel or ceramic can be adopted, but is not limited thereto.

  As the circuit / pump integrated structure described above, the control circuit CC of at least one of the first vacuum pump P1 and the second vacuum pump P2 is accommodated in the casing BX, and the casing A structure in which BX is integrated with at least one of the vacuum pumps (P1 or P2) can be employed, and is not limited to the above example.

  In the exhaust system S1 of FIG. 1, a third vacuum pump P3 is further arranged and connected downstream of the second vacuum pump P2.

  In the exhaust system S1 of FIG. 1, a connection part C2 (second connection part) for connecting the second vacuum pump P2 and the third vacuum pump P3 is a pipe PL1 for connecting both the vacuum pumps P2, P3, The valve VL1 and the like provided in the middle of the pipe PL1 are included, and the gas discharged from the exhaust port 71 of the second vacuum pump P2 passes through such a pipe PL1 and the valve VL1 to the third vacuum. Transition to pump P3.

  In the case of a configuration including the third vacuum pump P3 as in the exhaust system S1 of FIG. 1, the << first gas condensing environment >> or << second gas condensing environment >> shown below can be employed. .

<< First gas condensation environment >>
The first gas condensing environment is an environment in which the environment inside the second vacuum pump P2 is included in the solid phase region above the vapor pressure curve VPC of the condensable gas flowing through the inside. With respect to the setting of such an environment, for example, the inside of the second vacuum pump P2 is held at a predetermined temperature by the heat-retaining function of the second vacuum pump P2, and thereby the predetermined temperature is set inside the second vacuum pump P2. This can be achieved by the corresponding pressure exceeding the vapor pressure curve VPC of the condensable gas.

<< Second gas condensation environment >>
The second gas condensing environment is above the vapor pressure curve VPC of the condensable gas in which the internal environment of the connecting portion C2 connecting the second vacuum pump P2 and the third vacuum pump P3 flows. This environment is included in the solid phase region. Regarding the setting of such an environment, for example, the inside of the connection part C2 is maintained at a predetermined temperature by keeping the temperature of the connection part C2, so that the pressure corresponding to the predetermined temperature is maintained in the connection part C2. It can be realized by exceeding the vapor pressure curve VPC.

  When the << first gas condensing environment >> is employed, gas condensing is performed inside the second vacuum pump P2, specifically in a gas exhaust passage formed by a gap between the rotating body and the surrounding fixed portion. And the condensed components of the gas adhere to the gas exhaust passage. The condensed component of the adhering gas can be removed quickly and effectively by utilizing the mechanical structural characteristics of the second vacuum pump P2.

  That is, the second vacuum pump P2 is composed of a volume transfer pump DP1 such as a Roots pump as described above, and the rotary body inside the pump is a fixed part around it or the other rotary body. And it is structured to rotate with a small gap. For this reason, when the thickness of the condensed component of the gas attached as described above becomes larger than the gap around the rotating body, the gas is surely removed in a form that is scraped off by the rotating body. In order to prevent the condensed component of the gas scraped off as described above from flowing back to the upstream side, the second pressure is set so as to exceed the vapor pressure curve VPC of the condensable gas in the vicinity of the exhaust port 71 of the second vacuum pump P2. It is preferable to set the temperature of the vacuum pump P2.

  When the << first gas condensing environment >> is employed, as a specific method for recovering the condensed components of the gas scraped off as described above, for example, as shown in FIG. 1, the second vacuum pump P2 is used. It is conceivable to attach a precipitate collection tank TK directly below the exhaust port 71 via a straight pipe type pipe PL2. According to this method, the condensed component of the gas scraped off as described above passes through the pipe PL2 and the valve VL2 in the middle thereof and falls into the precipitate collection tank TK and is collected.

  In the case where the << first gas condensing environment >> is employed, when the second vacuum pump P2 is stopped, the temperature of the second vacuum pump P2 decreases, and its pump components, that is, the rotating body and its It is preferable to perform the above-described scraping operation by performing a so-called idling operation that is performed at a low speed until the surrounding fixing members are thermally contracted. This is to prevent problems such as locking of the rotating body of the second vacuum pump P2 due to the condensed component of the gas that has not been shaved off.

  On the other hand, when the << second gas condensing environment >> is employed, the connecting portion connecting the second vacuum pump P2 and the third vacuum pump P3 downstream, specifically, the second vacuum pump P2. Since gas condensation occurs in C2, as shown in FIG. 7, a trap TR1 or a storage tank that traps the condensed or solidified (or solidified) gas component in the middle of the pipe PL1 constituting the connecting portion C2 By providing the capturing means TR, the condensed gas component can be captured.

  That is, the trap TR1 or the inside of the trap TR or the inside of the storage tank is an environment included in the solid phase region above the vapor pressure curve VPC of the condensable gas flowing through the trap TR, Gas condensation occurs inside the trapping means TR such as a storage tank, and the condensed gas component can be trapped by the trapping means TR.

  For example, as shown in FIG. 7, the trap TR1 includes a pressure vessel 80, a plurality of plate-like members 81 (trap plates) installed in the pressure vessel 80, the inside of the pressure vessel 80, and the plate-like member. A refrigerant flow path 82 through which a refrigerant (cooling water or the like) for cooling 81 flows, and the inside of the pressure vessel 80 and the plate-like member 80 are cooled by the refrigerant, thereby condensing in the pressure vessel 80. You may comprise so that the condensed gas component may adhere to the plate-shaped member 80 by condensing gas. In this case, the plate-like member 81 is installed in parallel with the gas flow. This is to prevent the gas flow from being obstructed by the plate-like member 81. The storage tank may be configured similarly to the trap TR1.

  Maintenance of the trap TR1 may be performed by closing the manual valve VL3 and the electromagnetic valve VL1 provided in the middle of the pipe PL1 constituting the connection portion C2, opening the pressure vessel 80, and taking out and replacing the plate member 81. At this time, although not shown in the figure, the valve VL3 is double installed so that the plate-like member 81 is taken out and replaced while the condensed component of the gas accumulated in the trap TR is sealed in the pressure vessel 80. May be.

  8 and 9 are configuration diagrams of an exhaust system according to another embodiment of the present invention.

  In the exhaust system S1 of FIG. 1, a structure in which the first vacuum pump P1 and the second vacuum pump P2 are connected and integrated through the connection portion C1 is used. Instead, the structure shown in FIG. Like the exhaust system S2, the first vacuum pump P1 and the second vacuum pump P2 are separated, and the second vacuum pump P2 is connected in series near the separated first vacuum pump P1 via the connection portion C1. You may employ | adopt the structure connected. In this case, the connecting part C1 is constituted by a pipe PL4, and gas moves from the first vacuum pump P1 toward the second vacuum pump P2 through the pipe PL4.

  In the exhaust system S2 of FIG. 8, the turbo molecular pump TP2 including the large-diameter exhaust port 57 shown in FIG. 10 can be adopted as the first vacuum pump P1. Since the basic configuration of the turbo molecular pump TP2 shown in FIG. 10 is the same as the configuration of the turbo molecular pump TP1 shown in FIG. 3, the same reference numerals are given to the same members, and the detailed description thereof is as follows. Omitted.

  In the positive displacement pump DP1 employed as the second vacuum pump P2, a rotor that is long in the direction of the rotation axis may be used as the rotating body. In this case, the second vacuum pump P2 (the positive displacement pump DP1) The suction ports 70 are rectangular or a plurality of the suction ports 70 are arranged in a line. For this reason, as the piping PL4 in the exhaust system S2 of FIG. 8, it is preferable to employ, for example, the piping PL4 having the shape shown in FIG.

  As described above, the exhaust system S2 in FIG. 8 is also provided with the second vacuum pump P2 in the vicinity of the first vacuum pump P1, so that the exhaust system S2 in FIG. The environment can be set so as to be an environment included in the gas phase region below the vapor pressure curve of the condensable gas flowing through the inside, and the same effect as the exhaust system S1 of FIG. 1 can be obtained.

  Incidentally, in the exhaust system S2 of FIG. 8, the L-shaped pipe PL4 is adopted as a specific configuration of the connecting part C1, but instead, the straight pipe type pipe PL5 shown in FIG. 9 is connected to the connecting part C1. By adopting as, it is also possible to adopt a configuration in which the second vacuum pump P2 is installed in the vicinity immediately below the first vacuum pump P1. Since the pressure loss due to the fluid frictional resistance of the gas is smaller in the straight pipe type PL5 than in the L type pipe PL4, the straight pipe type is used in adopting the above-described “measures against gas condensation in the present invention”. It is considered that the pipe PL5 is more suitable.

  The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

  In the present invention, the vapor pressure curve diagram of FIG. 2 has been described as an example in which the condensable gas undergoes a phase change from gas to solid, but when the gas changes from gas to liquid, or from gas to liquid through solid Including the case of phase change, the same effect can be obtained.

BT1 Bolt BX Housing CC Control circuit C1, C103 Connection portion C2 of the first vacuum pump and the second vacuum pump Connection portion DP2 of the second vacuum pump and the third vacuum pump DP1 Volumetric pump DN1, DN2, DN3 , DN4 Vibration absorber DC color (heat insulation color)
DD Heat insulation means DG Air gap (heat insulation space)
G1 Gap H Communication hole P1, P101 First vacuum pump P2, P102 Second vacuum pump PL1, PL2, PL3, PL4, PL5, PL6 Piping RD1, RD2 Annular elastic members S1, S2, S3 Exhaust system S100 of the present invention Conventional exhaust system SP Spacer TK Precipitate collection tank TP1, TP2, TP3 Turbo molecular pump TR Trapping means TR1 Trap VC Anti-vibration structure VL1, VL2, VL3 Valve VPC Vapor pressure curve WP Compound pump 50 Blade exhaust mechanism 51 Rotary blade 52 Fixed Blade 53 Magnetic bearing 54 Rotor 55 Pump case 56 Suction port 57 of the first vacuum pump (turbo molecular pump) 58 Exhaust port 58 of the first vacuum pump (turbo molecular pump) Water cooling pipe 59 Water cooling plate 60 Water cooling means 70 Second Vacuum pump inlet 71 Second vacuum pump outlet 80 Pressure vessel 81 Plate member 82 Refrigerant flow path

Claims (17)

In an exhaust system in which a first vacuum pump and a second vacuum pump are connected in series as at least two pumps, and a gas containing a condensable gas is exhausted through the vacuum pump and its connection part.
The second vacuum pump is installed in the vicinity of the first vacuum pump, and the pressure of the condensable gas flowing through the inside of the connecting portion is reduced by lowering the pressure inside the connecting portion. An exhaust system characterized in that the environment is set in a gas phase region below the curve. The exhaust system according to claim 1, wherein the first vacuum pump and the second vacuum pump are connected and integrated. The exhaust system according to claim 1, wherein a vibration-proof structure is provided in the connection portion. The exhaust system according to claim 1, wherein the first vacuum pump is located upstream of the second vacuum pump and includes a turbo molecular pump. The exhaust system of claim 4 wherein the turbo-molecular pump, which includes a blade pumping mechanism for exhausting the gas in the rotor blades and the stationary blades, characterized in that has a structure without the drag pumping mechanism. The exhaust system according to claim 1, wherein the second vacuum pump is located downstream of the first vacuum pump and includes a positive displacement pump. The positive displacement pump includes a heater for heating the inside of the pump, a temperature sensor for measuring a temperature in the pump, and a temperature control for controlling a heating temperature of the heater using a measurement value of the temperature sensor. The exhaust system according to claim 6 , further comprising a circuit. The exhaust system according to claim 6 , wherein the positive displacement pump includes an inverter circuit, and the rotation speed can be changed by the inverter circuit. The exhaust system according to claim 6 or 8 , wherein the positive displacement pump has a low-speed operation function that enables operation at a rotational speed lower than a rotational speed during normal operation. A control circuit for at least one of the first vacuum pump and the second vacuum pump is housed in a housing, and the housing is connected to at least one of the vacuum pumps. The exhaust system according to claim 2, wherein the exhaust system has an integrated structure. 11. The exhaust system according to claim 10 , wherein a heat insulating means is provided at a connection portion between the first vacuum pump or the second vacuum pump and the housing of the control circuit. The exhaust system according to claim 1, wherein a third vacuum pump is disposed and connected downstream of the second vacuum pump. The environment inside the second vacuum pump is set so as to be an environment included in a solid phase region above the vapor pressure curve of the condensable gas flowing inside the second vacuum pump. The exhaust system described. The environment inside the second connection part connecting the second vacuum pump and the third vacuum pump is included in the solid phase region above the vapor pressure curve of the condensable gas flowing through the inside. The exhaust system according to claim 12 , wherein the exhaust system is set to be an environment. The trap or storage tank which captures the condensed or solidified gas component is provided in the 2nd connection part which connects the 2nd vacuum pump and the 3rd vacuum pump to Claim 14 characterized by things. The exhaust system described. Vacuum pump constituting an exhaust system according to claims 1 15. The component of the vacuum pump of Claim 16 .

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